From 5f5a2d1c3c26554758782cf6c047bda6eca4d8f3 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Mon, 29 May 2017 14:57:23 +0000
Subject: [PATCH 1/2] Avoid unnecessary calls to fstat() to determine the
 database file size.

FossilOrigin-Name: c733a1dea37e4678e7bd0d3d0ca9b8eae1fbdc28615f75d8f1e5141aa53567d9
---
 manifest      | 15 +++++++++------
 manifest.uuid |  2 +-
 src/pager.c   | 13 ++++---------
 3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/manifest b/manifest
index 563124269d..4ff4f00aa2 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\stypo\sin\sa\scomment.\s\sNo\scode\schanges.
-D 2017-05-29T14:30:46.634
+C Avoid\sunnecessary\scalls\sto\sfstat()\sto\sdetermine\sthe\sdatabase\sfile\ssize.
+D 2017-05-29T14:57:23.932
 F Makefile.in 1cc758ce3374a32425e4d130c2fe7b026b20de5b8843243de75f087c0a2661fb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 8eeb80162074004e906b53d7340a12a14c471a83743aab975947e95ce061efcc
@@ -391,7 +391,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 30e2c43e4955db990e5b5a81e901f8aa74cc8820
 F src/os_win.c 2a6c73eef01c51a048cc4ddccd57f981afbec18a
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c b9e2eac73c63ecb208ed56ce4db30d3ac70d367814a1d55108c1d15805a3e59d
+F src/pager.c a656a65be35c03b20513017a2d45c90721ce1de549115d3c524f204603b6c58c
 F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
 F src/parse.y 0513387ce02fea97897d8caef82d45f347818593f24f1bdc48e0c530a8af122d
 F src/pcache.c 62835bed959e2914edd26afadfecce29ece0e870
@@ -1581,7 +1581,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 6854a34ed708259f2280f7ee56cec09f7fc99810dc739dc2814ddeae286aa2c4
-R 51f95c83705d5e49164e8a8e656ed857
+P cb29b838886769afe866b1172e3d5d7e36387149b79c51f91cf59da3f4a5f25b
+R bc8c78eb6e446da4e629bd6e66214ab1
+T *branch * io-opt
+T *sym-io-opt *
+T -sym-trunk *
 U drh
-Z ba73033214a9ed109f3bb3430dcbffef
+Z 5a21d8f44598546293f21185a73b0f86
diff --git a/manifest.uuid b/manifest.uuid
index f4be47a677..1d262da355 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-cb29b838886769afe866b1172e3d5d7e36387149b79c51f91cf59da3f4a5f25b
\ No newline at end of file
+c733a1dea37e4678e7bd0d3d0ca9b8eae1fbdc28615f75d8f1e5141aa53567d9
\ No newline at end of file
diff --git a/src/pager.c b/src/pager.c
index cdc5751e81..c2c97d42f8 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -5263,19 +5263,14 @@ int sqlite3PagerSharedLock(Pager *pPager){
       ** detected.  The chance of an undetected change is so small that
       ** it can be neglected.
       */
-      Pgno nPage = 0;
       char dbFileVers[sizeof(pPager->dbFileVers)];
 
-      rc = pagerPagecount(pPager, &nPage);
-      if( rc ) goto failed;
-
-      if( nPage>0 ){
-        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
-        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
-        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+      IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
+      rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
+      if( rc!=SQLITE_OK ){
+        if( rc!=SQLITE_IOERR_SHORT_READ ){
           goto failed;
         }
-      }else{
         memset(dbFileVers, 0, sizeof(dbFileVers));
       }
 

From 77f6af2b9600a30936abf9901a813f08e0c1056c Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Mon, 29 May 2017 16:45:45 +0000
Subject: [PATCH 2/2] Avoid unnecessary fstat() calls to determine the database
 size when transitioning into a read transaction on a rollback-mode database.

FossilOrigin-Name: 6c3476b513965df22d648f9a1b99733af753b44d51163cc7d42a69bf562300e1
---
 manifest      | 15 ++++++---------
 manifest.uuid |  2 +-
 src/pager.c   | 28 +++++++++++++---------------
 3 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/manifest b/manifest
index 4ff4f00aa2..a0f87bf4e5 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Avoid\sunnecessary\scalls\sto\sfstat()\sto\sdetermine\sthe\sdatabase\sfile\ssize.
-D 2017-05-29T14:57:23.932
+C Avoid\sunnecessary\sfstat()\scalls\sto\sdetermine\sthe\sdatabase\ssize\swhen\ntransitioning\sinto\sa\sread\stransaction\son\sa\srollback-mode\sdatabase.
+D 2017-05-29T16:45:45.492
 F Makefile.in 1cc758ce3374a32425e4d130c2fe7b026b20de5b8843243de75f087c0a2661fb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 8eeb80162074004e906b53d7340a12a14c471a83743aab975947e95ce061efcc
@@ -391,7 +391,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 30e2c43e4955db990e5b5a81e901f8aa74cc8820
 F src/os_win.c 2a6c73eef01c51a048cc4ddccd57f981afbec18a
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c a656a65be35c03b20513017a2d45c90721ce1de549115d3c524f204603b6c58c
+F src/pager.c 14f6982c470c05b8e85575c69e9c1712010602e20400f8670d8699e21283e0e4
 F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
 F src/parse.y 0513387ce02fea97897d8caef82d45f347818593f24f1bdc48e0c530a8af122d
 F src/pcache.c 62835bed959e2914edd26afadfecce29ece0e870
@@ -1581,10 +1581,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P cb29b838886769afe866b1172e3d5d7e36387149b79c51f91cf59da3f4a5f25b
-R bc8c78eb6e446da4e629bd6e66214ab1
-T *branch * io-opt
-T *sym-io-opt *
-T -sym-trunk *
+P c733a1dea37e4678e7bd0d3d0ca9b8eae1fbdc28615f75d8f1e5141aa53567d9
+R 305c14b2512f47cedccd7e2033ab5eaa
 U drh
-Z 5a21d8f44598546293f21185a73b0f86
+Z e2a7cd050c361ca9085d24d8c34886c7
diff --git a/manifest.uuid b/manifest.uuid
index 1d262da355..e224b6b0b6 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-c733a1dea37e4678e7bd0d3d0ca9b8eae1fbdc28615f75d8f1e5141aa53567d9
\ No newline at end of file
+6c3476b513965df22d648f9a1b99733af753b44d51163cc7d42a69bf562300e1
\ No newline at end of file
diff --git a/src/pager.c b/src/pager.c
index c2c97d42f8..aee50e5318 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -3304,23 +3304,21 @@ static int pagerOpenWalIfPresent(Pager *pPager){
 
   if( !pPager->tempFile ){
     int isWal;                    /* True if WAL file exists */
-    Pgno nPage;                   /* Size of the database file */
-
-    rc = pagerPagecount(pPager, &nPage);
-    if( rc ) return rc;
-    if( nPage==0 ){
-      rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
-      if( rc==SQLITE_IOERR_DELETE_NOENT ) rc = SQLITE_OK;
-      isWal = 0;
-    }else{
-      rc = sqlite3OsAccess(
-          pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
-      );
-    }
+    rc = sqlite3OsAccess(
+        pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
+    );
     if( rc==SQLITE_OK ){
       if( isWal ){
-        testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
-        rc = sqlite3PagerOpenWal(pPager, 0);
+        Pgno nPage;                   /* Size of the database file */
+
+        rc = pagerPagecount(pPager, &nPage);
+        if( rc ) return rc;
+        if( nPage==0 ){
+          rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
+        }else{
+          testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
+          rc = sqlite3PagerOpenWal(pPager, 0);
+        }
       }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
         pPager->journalMode = PAGER_JOURNALMODE_DELETE;
       }